The better cards have custom cooling, like Asus DC2T ,Sapphire Vapor-X or Flex , MSI Twin Frozr or Lightning , Gigabyte OC Editions , XFX OC Editons or Evga OC , these have better cooling and are overclocked.
Not sure if XFX still offer the lifetime warranty for this card. I believe it's the only brand that DOES NOT come with an active display port adapter for eyefinitiy. Other than that,they are all pretty much the same at this stage. The warranty length seems to be the only difference between the brands. The Saphire 7970 flex 6GB (leaked apparently) certainly sounds interesting for a mutli screen set up.